Oil and gas fires, especially where the oil and/or gas are under pressure, are difficult to extinguish and involve great risk to the persons who must use explosives in the process. Even when large quantities of water are sprayed to cool the fire, there are considerable risks involved.
Even when, for example, an explosive charge can extinguish the flames by cutting off the supply of oxygen, the metal pipes and surrounding areas are so hot that the fire can restart if the well cannot be capped quickly enough after the blast from the explosion to extinguish the flames. Also, the blast must be of sufficient force to provide an adequate shock wave, but not be so destructive as to prevent the well from being capped.
While cooling water is readily available for oil fires on offshore rigs, there has been a continuing problem of fighting fires in desert regions where tracked vehicles and helicopters are required to even reach the site and water is unavailable.